Method of skiatron cleanup



July 24, 1951 H. c. KELLY METHOD OF' SKIATRON CLEAN-UP Filed Dec. 10,1945 mo muDOw moo-.Eko mo momsom INVENTOR HARRY C.KELLY ATTORNEYreviously mentioned Patented July 24, 1951 UNITED STATES rATENr opweg" li; t t i METHOD F cLEAtJP y.

Harry C. Kelly,

Belmont, Masts.,-

assvignor, by

mesne assignments, to =the-@United .States of i America, as representedby the Secretary of the Navy Application December 1o, 1945, serial Ne.534,108

Claims.y

"k-This invention relates to skiatrons or dark is known as burn-in, andis often objectionable. When it is desired to apply a different patternOther objects and advantages of this inven-y tion will be apparent fromthe following speci cation when are means genfor focusing the electronand means 20 for gating the cathode 2l of the skiatron. The s additionalclean-up means for defocusing the electron `means 23 for reducing thevelocity of the `electron beam, 24 for inelectron beam, means 25, 26 forremoving cathode gating means 20, andoptionallyA usable means generallydesignated 21 intercleaneup means aise ineide means 22 beam of the.-skiatron,

for simultaneousl operation when sired. When these clean-up means areoperated simultaneously the sweep sifled and defocused electron beam onthe screen lcreasing the speed of clean-up.

Sweep means l2 comprises sweep coils 32, a source" of normal current 33,and rotating 34 mechanically connected to coil 32, as indicated bydotted line 35. Rotating means 34 turns coil'32, and in combination withsource=33 coil 32 to either source 33 or, when desired, to source I3.

Focusing means l5 comprises focus coils 36 beam on the'screen Il. lowerposition resistor 22 1s connected in c mal operatingcondition switch 31is in the upper position. I n 4Source ofanode voltage I 6 provides agating to either source I 6 provides a reduced .Means I4 comprises ay D.C. voltage increases the screen Il.

Means I8 for biasing grid I9 comprises a source 39 of D. C. voltageconnected by switch 49 to the grid. This D. C. voltage, durinvgnnorv"alroperat: ing conditions/keeps the tubI 'ghtl-Sfv abv? cut-E. L .vMeans 24 for intensifying the electron beam of tube I0 comprises asource 24 of decreased voltage, which when applied to grid figintensiesff the electron beam. For normal operation sw'tch 40 connects grid I9 tosource 39'VH For cle' of the skiatron switch 4I)v conn i source 24.

Means for gating cathode 2l comprises a which when applied to anode I1total number of electrons striking mal operation is connected by switch2li/,to cathode 2 I. To remove the lcathode gating ineansfor" clean-up,switch 26 connects cathode 2| by lead 2 -to ground. if? 'ffl: Means 21interconnects Yallo'f the additional cleanup means -iorA-sim'ultia`.r1eoi'1s ioperatibn. 'Ihs comprises mechanical'v-couplings,designated by dotted lines 42, 43, 44, k45, and`4'6, for fall-of theswitches and coupling `3I` `for remcivingV h'a't absorber 29. "f 1 "Theoptical projection means28 i'sfaconventional Schmidt 'projectionsysternffcomprising' lamp 30, reflector,'heatabsorber 29 l'er'isesE 4'8,49 fand 5I), mirror 54, spherical mirrorf I ,correct ing lens52 andviewing-screen 53. l Using this the-ski system `an venlarged'vrepresentation* of atron pattern is available at viewing 4screerril'.

" 4'When clean-up' is desired, switch`l4'connects source I3 ofs'me'wave'current'tosweep coil '32', means 31 removes heat absorber1'29Ifrom 'the optical' projectionsystem 28, switch 31 connects resistor 22series'withfocus `coil connects source `23 of Adecreased-anode voltagetoanodefll, switch`40 connects'source 24 of =de` creased bias `supply togrid I9; and switch-'226 grounds/cathode 2l. This results inanuintensieed Yand'- defocused electron Abeam-striking screen II, and producesthereon aisweepfwhih travels completely across thel screeninsteadiff`starting from the center. This application-of :electron bombardment,along' with yheat from:v therlight source 30, removes theburned-'insignalsina=very short time. f L *Itis to be understood thatwhile "thisspecifr cation has described vthe theory Eo'r' theinventionas used with a projection system, the inventioniis not necessarilylimited thereto. i f apparentr to a person skilled in the art, thisinventionf-is applicable to any apparatus `employing'a skiatron. v f'What is claimed is:

l. i The combination with a'skiatron type l:tube and-deection meansfor'providing a radialsweep rotating yabout an origin on .the-screen,ofthe skiatron, 'of v additional meansl forl rapidly .cleaning-up -theskiatron screen, said meansk yincluding a second 'source of'sweep'energy which .f changes in polarity as well asaintensity; andfmeansoper' ative when desired, to connect saidsou-rce .tosaiddeflection means, vvwherebythe sweepY extends diametrically onboth-sides =of the origimfthereby increasing the speed of clean-up ofsaidskiatrcn.

2. The combinationnof clairnv1, inwhichcsad second source `ofsweepenergy Ais-za sine-@wave SOlllCe. .:g':` i; f 'i 3. The combinationv"with apparatusv including a skiatron type tube, a deflection meansioripro' viding'a radiali-sweep rotatingcabout anorigin on .hasta i saidelectron beam,

the screen, means for focusing the electron beam of said skiatron, asource of anode voltage for the rst anode of said skiatron, means forbiasing the grid of said skiatron, and means for gating the cathode ofsaid skiatron, o additional means for rapidly cleaning-up the screen ofsaid skiftromisaid clean-up means including, a second 'source' of' sweep'energy providingv a sine wave, means operative when desired to connectsaid second source of sweep energy to said deflection .,rneans, meansfordefocusing said electron beam, means for reducing the velocity of saidelectron beam. io'flws'aid skiatron, means for intensifying means forremoving said means, and optionally usable means interconnecting all ofthe aforesaid cleanclean-upv is desired, whereby the sweep, formedbyi'ianintensied and defocused electron beam on the screen, extendsdiametrically on both sides ffiztheffzorigin, 'thereby increasing thespeed'of clean-up` of saidsfskiatron. i -f f4; LThe 4coinrbination withafskiatron projection system including a skiatron type tubeadeectionmea'ns for providing al radial sweep rotating aboutzianforigin `onthe screen, and optical project-irr-me '-nsf'including a heat absorberfor providing-a distant imag'e'of the screen pattern, ofadditionalrmeans for rapidlyHcleaning-up the screen or said "skiatron,said clean-up means including, :ai second source' of sweep energyproviding a sinev wave,4 mea-nsfr operative when desired tcrconnectfsaidsecondI source `of sweep energy to said f deflection means,A lmeans forr removing .the heat absorber of said optical projectio n'means-toapplyiheat to said fscreen, and optionally usable means-interconnectingthe vaforesaid clean-up means for simultaneous operation when clean-upisidesired, wherebythefsweep, formed on a heatedscreen;extendsfdiametrically on' bothv sides of the orgin,-therebyincreasing the speedof Aclean-up ci?fsaid.'.skiatronV f 'Y 5. Thecombination with alskiatron projectioncsystem incl 'ding a skiatrontype-tube; a deflection# meansfor :providing-a radial' sweeprotating:about an'origin onwthe screen, an optical projection meansincluding a -heat absorber ioriwproviding a rdistant image of thescreenpattern, means for focusing the electron beam of said ;yslriatrongf-y a :source 'of anode voltage for' the iirstfaanode-'ofsaid-fskiatron, means for biasing the.;grid or'saidskiatron, and meansfor gating thefcathodeofsaid skiatron, of additional means forrapidly.-.cleaninguptthe screen of said-skiatrDn,f-.sa id clean-up-meansincluding, a `second sourcev'oi sweepA energy a sine wave; meansoperativawhen desired to connect said second source :ofi sweep energy'to said deilection means, means for .deocusing said electron beam, ythe heat absorber of said optical projection rmeans to apply heat ltosaid screen, means for removing anode gating voltage, means f-ior,intensifying' said electron beam, means for ,removing said `cathodegating means, andV optionallyusable A meansl interconnecting all or theaforesaid clean-up means n operationrlwhen clean-up is desired, wherebythe sweep, formedv by an intensified and defocused electronbeam on aheated screen, extends `diametrically on both sidesv "of thelorigi'n,therebyv increasingjthe speedof Y'clean-'up of 'said 'skiatromvI5 said'fscreen,"meansfforapplyingapotentialstosaid the operatingpotentials of said tube to produce an intensified defocused beam,applying a sinusoidal sweep voltage to provide electron bombardment ofsaid screen, and applying heat energy to said screen.

ing heat energy to said screen.

9. Apparatus applies heat energy and electron bombardment n to saidscree 10. In a dark trace cathode ray projection system including askiatron type tube, deection ap- HARRY c. KELLY.

REFERENCES CITED The following references yare of record in the le ofthis patent:

UNITED STATES PATENTS Number Re. 22,734 2,276,359

Number Name Date Rosenthal Mar. 19, 1946 Von Ardenne Mar. 17, 1942FOREIGN PATENTS Country Date Great Britain May 26, 1941

